Hydrothermal synthesis of cobalt carbonates using different counter ions: An efficient precursor to nano-sized cobalt oxide (Co3O4)

Synthesis of submicrometer crystalline particles of cobalt carbonate was achieved hydrothermally using different cobalt salts and urea with a molar ratio from 1:3 to 1:20 (cobalt salt:urea) in aqueous solutions at 160 °C for 24–36 h, in the presence of cetyltrimethylammonium bromide (CTAB) as a surfactant. Nanoparticles of Co3O4, with an average size from 30 to 39 nm, were obtained by thermal decomposition of CoCO3 samples at 500 °C for 3 h in an electrical furnace. The as-synthesized products were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–Vis spectra and thermal analysis. Studying the optical properties of the as-prepared cobalt oxide nanoparticles showed the presence of two band gaps, the values of which confirmed the semiconducting properties of the prepared Co3O4.

Submicrometer crystalline particles of cobalt carbonate with different morphologies can be prepared by a hydrothermal process using cobalt acetate, cobalt chloride or cobalt nitrate, and urea in the presence of cetyltrimethylammonium bromide (CTAB) as a surfactant. Squared-shape nanoparticles of Co3O4, with an average size from 30 to 39 nm can be produced by calcination of the CoCO3 samples at 500 °C for 3 h. The as-prepared cobalt oxide nanoparticles show some optical properties such as the presence of two band gaps with values in the range 1.94–1.49 eV, which confirm the semiconducting properties of the prepared Co3O4 nanoparticles.Figure optionsDownload as PowerPoint slideHighlights
► Nanocrystalline Co3O4 powders are prepared by thermal decomposition.
► The crystalline particles of cobalt carbonate with different morphologies are prepared by a hydrothermal method.
► The cobalt oxide nanoparticles have been optical properties in range 1.94–1.49 eV.
► The products were characterized by XRD,TG, FT-IR, TEM, SEM, UV–Vis spectra.